Devices of this kind are used in particular in steam generators or boilers in which the problem often arises of suspending masses (such as collector manifolds) on the walls of combustion chambers in which the tubes for conveying a flow of water to be boiled are subjected to large expansions and contractions as a function of the temperature of the fluid flowing therein. These manifolds are placed in a cantilevered-out position relative to the wall constituted by the tubes, and it is essential for them to follow the displacements of the wall without transmitting forces to the wall that could deform it.
Proposals have already been made to suspend such manifolds from spring supports which are designed to take up a fraction of the weight of the cantilevered-out mass, while nevertheless being capable of following the displacements of the mass without excessive variation in the force they provide. However, such springs act only as counterweights, and they control the vertical position of the mass only at the cost of parasitic forces on the walls of the combustion chamber, which forces are all the greater since the force to be taken up by the spring is not constant, depending, as it does, on forces of varying magnitude applied by the pipework connected to the manifolds. Furthermore, the manifolds do not remain completely stationary relative to the wall of the combustion chamber.
Proposals have also been made to support such collector manifolds by vertical carrier tubes conveying a fluid which causes them to expand thermally by an amount equal to the expansion of the wall of the steam generator. The manifolds are then indeed stationary relative to the wall of the combustion chamber. However, such devices are complex and expensive, and their operation can be disturbed either because of a delay in the thermal expansion of the vertical carrier tubes relative to that of the wall of the combustion chamber, or else because of poor circulation of the fluid in the carrier tubes. As a result, equal thermal expansion no longer occurs in the vertical carrier tubes and the wall of the combustion chamber, and this can lead to unacceptable stresses appearing in the wall.
Proposals have also been made in document FR-A-2 269 023 to take up the cantilevered weight of manifolds or burners in combustion chambers by means of lever systems having pivot points secured to a stationary framework and disposed in such a manner that the displacements of the support point for the manifold or the burner are equal to the displacements of the connection point on the wall of the combustion chamber. However, the levers in those systems are subjected to bending, and their total accumulated bending deformation degrades overall stiffness, unless they are themselves overdimensioned.
Finally, document FR-A-2 640 356 proposes a support device comprising firstly a hinged plane support on which the cantilevered-out mass is placed, and secondly a system of three hinged arms connecting the fixed framework to the moving element and the plane support.
The various components of that device are not subjected to bending stresses, but only to stresses in traction or compression.
However, that device is relatively complicated since it requires three hinged arms.
An object of the present invention is to provide a rigid support device for such cantilevered-out masses, which is simpler while having displacements that follow more accurately the displacements of the vertically movable element.